Biodegradable magnesium(Mg)alloys have received much attention due to their biocompatibility and biodegradation.In this study,to uncover the effects of grain morphologies,including grain size and distribution on mecha...Biodegradable magnesium(Mg)alloys have received much attention due to their biocompatibility and biodegradation.In this study,to uncover the effects of grain morphologies,including grain size and distribution on mechanical and corrosion properties,biodegradable Mg-2.1Nd-0.2Zn-0.5Zr(wt.%)(denoted as JDBM)alloy mini-tubes for stent application with three typical microstructures were achieved success-fully by adjusting drawing parameters.Samples with the bimodal structure exhibit the highest strengthductility balance attributed to the combined effects of fine grains and coarse grains,but show the fastest corrosion rate of about 1.00±0.136 mm/year mainly due to the formation of micro galvanic couples between coarse and fined grains.Samples with fine equiaxed grains show the lowest corrosion rate of about 0.17±0.059 mm/year,as well as uniform corrosion mode and mechanical properties of yield strength(YS)256±5.7 MPa,ultimate tensile strength(UTS)266±3.8 MPa,and elongation to failure(EL)13.5%±1.8%,attributed to the high-density grain boundaries.Samples with coarse equiaxed grains exhibit medium corrosion resistance and mechanical properties of about 175±4.8 MPa,221±4.0 MPa,and 21.53%±4.1%.Considering the mechanical and in vitro corrosion properties,biodegradable JDBM alloy implants are recommended to be composed of fine equiaxed grains,which can be used as microstructural targets for fabrication and processing.展开更多
The production of mini-tubers under soilless cultivation system increased the availability of pathogen-free seed potatoes. The objective of this study was to evaluate the rooting capability of mini-cuttings of potato ...The production of mini-tubers under soilless cultivation system increased the availability of pathogen-free seed potatoes. The objective of this study was to evaluate the rooting capability of mini-cuttings of potato clones as a function of the irrigation solution and the physiological age of the mother plant, under soilless cultivation system. Potato mini-cuttings were collected from young and mature plants of the cultivars Asterix and Macaca and the advanced clone SMINIA 793101-3. The young plants were newly acclimatized individuals and the mature plants were at the stage of producing mini-tubers. In the first experiment, mini-cuttings originating from summer pruning of mature plants were grown under closed soilless cultivation system irrigated with a nu- trient solution developed for the production of potato mini-tubers and a solution comprised of tap water only. The experiment was conducted in a 3 × 2 factorial arrangement (clones and irrigation solutions) in the complete random design with four replicates of 15 mini-cuttings. In the second experiment, the young and mature mini-cuttings were established under a closed soilless cultivation system irrigated with nutrient solution. The experiment was conducted in a 3 × 2 factorial arrangement (clones and physiological age of the mother plant) in the complete random design with four replicates of 15 mini-cuttings. In both experiments, the percentage of rooting and survival of mini-cuttings, number of roots and length of the longest root were assessed at 21 days of cultivation. Potato mini-cuttings can be rooted under closed soilless cultivation system irrigated with nutrient solution or tap water. Mini-cuttings of young plants have higher rooting capability compared to the ones taken from mature plants. The loss of rooting capability depends upon the potato cultivar.展开更多
An air-suction potato seed metering device was designed to improve the performance of the large-size seed crops planting equipment and provide a solution for problems on the mechanical potato seeder,such as high multi...An air-suction potato seed metering device was designed to improve the performance of the large-size seed crops planting equipment and provide a solution for problems on the mechanical potato seeder,such as high multiple-seeding index,high missing-seeding index,low qualified index,and limited versatility.The main structure and operation parameters in terms of rotating speed of the device,seeds height and pickup vacuum pressure were determined by theoretical analysis.Two orthogonal tests,conventional tuber(the triaxial average diameter is about 38-57 mm)test and mini-tuber(the triaxial average diameter is about 12-36 mm)test,were conducted to analyze the influences of these factors on the quality of seeding.The multiple-seeding index,missing-seeding index and qualified index were chosen for evaluating the working performance.The results of conventional tuber test showed that,the multiple-seeding index was 1.1%,the missing-seeding index was 0.8%and the qualified index was 98.1%under conditions of the 30 r/min rotating speed,25 cm seeds height and 10 kPa pickup vacuum pressure.The results of mini-tuber test showed that the multiple-seeding index was 0.5%,the missing-seeding index was 0.6%and the qualified index was 98.9%under conditions of 35 r/min rotating speed,17 cm seeds height and 3.5 kPa pickup vacuum.The working performances of the device can meet the requirements of precision seeding.展开更多
基金funded by grants from the National Natural Science Foundation of China(Nos.52130104 and 52273318)the Science and Technology Innovation Commission of Shenzhen Municipality(No.JCYJ20220818102815033)the National Key Research and Development Program of China(Nos.2021YFC2400701 and 2020YFE020210).
文摘Biodegradable magnesium(Mg)alloys have received much attention due to their biocompatibility and biodegradation.In this study,to uncover the effects of grain morphologies,including grain size and distribution on mechanical and corrosion properties,biodegradable Mg-2.1Nd-0.2Zn-0.5Zr(wt.%)(denoted as JDBM)alloy mini-tubes for stent application with three typical microstructures were achieved success-fully by adjusting drawing parameters.Samples with the bimodal structure exhibit the highest strengthductility balance attributed to the combined effects of fine grains and coarse grains,but show the fastest corrosion rate of about 1.00±0.136 mm/year mainly due to the formation of micro galvanic couples between coarse and fined grains.Samples with fine equiaxed grains show the lowest corrosion rate of about 0.17±0.059 mm/year,as well as uniform corrosion mode and mechanical properties of yield strength(YS)256±5.7 MPa,ultimate tensile strength(UTS)266±3.8 MPa,and elongation to failure(EL)13.5%±1.8%,attributed to the high-density grain boundaries.Samples with coarse equiaxed grains exhibit medium corrosion resistance and mechanical properties of about 175±4.8 MPa,221±4.0 MPa,and 21.53%±4.1%.Considering the mechanical and in vitro corrosion properties,biodegradable JDBM alloy implants are recommended to be composed of fine equiaxed grains,which can be used as microstructural targets for fabrication and processing.
基金CAPES(Coordination for the Improvement of Higher Education Personnel)for granting research scholarshipCNPq(National Council for Scientific and Technological Development)for partially funding the Potato Breeding and Genetics Program and for granting research scholarships.
文摘The production of mini-tubers under soilless cultivation system increased the availability of pathogen-free seed potatoes. The objective of this study was to evaluate the rooting capability of mini-cuttings of potato clones as a function of the irrigation solution and the physiological age of the mother plant, under soilless cultivation system. Potato mini-cuttings were collected from young and mature plants of the cultivars Asterix and Macaca and the advanced clone SMINIA 793101-3. The young plants were newly acclimatized individuals and the mature plants were at the stage of producing mini-tubers. In the first experiment, mini-cuttings originating from summer pruning of mature plants were grown under closed soilless cultivation system irrigated with a nu- trient solution developed for the production of potato mini-tubers and a solution comprised of tap water only. The experiment was conducted in a 3 × 2 factorial arrangement (clones and irrigation solutions) in the complete random design with four replicates of 15 mini-cuttings. In the second experiment, the young and mature mini-cuttings were established under a closed soilless cultivation system irrigated with nutrient solution. The experiment was conducted in a 3 × 2 factorial arrangement (clones and physiological age of the mother plant) in the complete random design with four replicates of 15 mini-cuttings. In both experiments, the percentage of rooting and survival of mini-cuttings, number of roots and length of the longest root were assessed at 21 days of cultivation. Potato mini-cuttings can be rooted under closed soilless cultivation system irrigated with nutrient solution or tap water. Mini-cuttings of young plants have higher rooting capability compared to the ones taken from mature plants. The loss of rooting capability depends upon the potato cultivar.
基金the China Agriculture Research System Special Foundation CARS-10-P22National Science and Technology Support Project 2014BAD06B03+1 种基金Yunnan Province Winter Pollution-free Yield Technology System Construction and Application Projects Funded 2014YNC001Heilongjiang Province Key Science and Technology Project GA15B401.
文摘An air-suction potato seed metering device was designed to improve the performance of the large-size seed crops planting equipment and provide a solution for problems on the mechanical potato seeder,such as high multiple-seeding index,high missing-seeding index,low qualified index,and limited versatility.The main structure and operation parameters in terms of rotating speed of the device,seeds height and pickup vacuum pressure were determined by theoretical analysis.Two orthogonal tests,conventional tuber(the triaxial average diameter is about 38-57 mm)test and mini-tuber(the triaxial average diameter is about 12-36 mm)test,were conducted to analyze the influences of these factors on the quality of seeding.The multiple-seeding index,missing-seeding index and qualified index were chosen for evaluating the working performance.The results of conventional tuber test showed that,the multiple-seeding index was 1.1%,the missing-seeding index was 0.8%and the qualified index was 98.1%under conditions of the 30 r/min rotating speed,25 cm seeds height and 10 kPa pickup vacuum pressure.The results of mini-tuber test showed that the multiple-seeding index was 0.5%,the missing-seeding index was 0.6%and the qualified index was 98.9%under conditions of 35 r/min rotating speed,17 cm seeds height and 3.5 kPa pickup vacuum.The working performances of the device can meet the requirements of precision seeding.
